San Antonio, TX · plumbing problem
Drains backing up in San Antonio
Updated · Editorial team; not yet technically reviewed
Short answer
SAWS says fats, oils and grease cause nearly 70% of sewer blockages and overflows in San Antonio. Grease congeals in pipes like cholesterol in arteries, whether in an 8-inch home line or a 3-foot main. If one drain is slow, it's usually a local clog; several backing up together point to the main line or lateral.
What's different in San Antonio
Fats, oils and grease account for nearly 70% of sewer blockages and overflows in San Antonio; historically about 75% of sanitary sewer overflows have been attributed to grease and debris. [1]
Grease includes more than cooking oil: dairy, the liquid on top of canned goods, peanut butter, fried foods, salad dressing, lard and even cake frosting. [1]
Residents should collect cooled grease in a disposable container for the trash or take it to the City's Household Hazardous Waste Drop-Off Center at 7030 Culebra Road. [1]
A 2012 city ordinance targets sewer blockages and overflows caused by grease discharged into the sanitary sewer. [2]
What you're seeing
| Symptom | Likely cause | Urgency |
|---|---|---|
| Kitchen sink slow | Grease in the branch | Soon |
| Tub fills when the toilet flushes | Main or lateral blockage | Urgent |
| Water in the outdoor cleanout | Blockage toward the street | Urgent; see lateral reimbursement |
What not to do
- Don't rinse greasy pans into the sink; wipe them first.
- Don't rely on the disposal; it doesn't stop grease.
- Don't pour hot water to 'melt' a clog; the grease re-sets farther down.
If it's past your property
A blockage found beyond your property may qualify for SAWS lateral reimbursement. Grease clogs clear best with hydro jetting.
You may also be dealing with
- SymptomSink not draining
- SymptomGurgling drains
- SymptomBasement flooding
- GuideWhy does my drain keep clogging?
Common questions
What causes most San Antonio sewer blockages?
Fats, oils and grease, nearly 70% of them according to SAWS.
Does peanut butter count as grease?
Yes, SAWS lists it along with dairy, fried foods, dressings and frosting.
Where can I drop off grease in San Antonio?
At the City's Household Hazardous Waste Drop-Off Center, 7030 Culebra Road, or in a sealed container in the trash.
Does San Antonio regulate grease in sewers?
Yes, a 2012 ordinance targets grease-caused blockages and overflows.
Why does grease clog home lines so easily?
It congeals and sticks to pipe walls, narrowing them over time.
Does a 3-foot sewer main clog from grease too?
Yes, SAWS says grease can block everything from an 8-inch home line to a 3-foot main.
What container should I use for grease?
An empty milk carton or frozen juice container works, SAWS says.
Why does my San Antonio tub fill when I flush?
A blockage downstream of both fixtures, usually in the main or lateral.
Can SAWS help if the clog is in the street?
A plumber-confirmed blockage beyond your property may qualify for reimbursement.
Does jetting fix grease-coated lines?
It scours grease from the walls better than a cable.
More plumbing help in San Antonio
- Backflow Testing in San AntonioSAWS backflow testing rules for San Antonio: the June 30 annual deadline, the codes behind it, reminder notices, and what a 10-day notice means.
- Toilet Installation in San AntonioSAWS toilet rebates in San Antonio: the current high-efficiency toilet rebate, which toilets qualify, SAWS's history of free toilet programs, and installation tips.
- Water bill suddenly high in San AntonioA high SAWS bill usually means a leak. How to find it, which leaks SAWS reviews for a credit, the 60-day deadline after repair, and the paperwork it wants.
- Sewer Line Repair in San AntonioSan Antonio sewer clogs: a licensed plumber clears your side, and if the blockage is past your property, SAWS may reimburse costs. Marking, the call and paperwork.
- Pipe Repair in San AntonioSAWS Plumbers to People: free repairs of leaking faucets, toilets and broken pipes for income-qualified homeowners, who qualifies, and what isn't covered.
- Frozen Pipe Repair in San AntonioFrozen pipes in San Antonio: pipes past the SAWS meter are the owner's, how to shut water off at the meter, SAWS freeze tips, and what not to do.
- Water Line Repair in San AntonioSAWS's service line inventory: over half of 600,000 lines unidentified, yearly letters to unknown, lead or galvanized lines, and free inspections for pre-1989 homes.
- Drain backing up: the full guideWhen water rises in a tub, shower or floor drain from another fixture, the main line is blocked. How to confirm it, what to stop doing and how it's cleared.
- Plumbing in San AntonioLocal water, housing and climate conditions, and the calls San Antonio homes need most.
How other cities handle it
- Drains backing up in BoiseWhy drains back up in Boise homes: grease is the city's top cause of sewer clogs, older neighborhoods are most at risk, and what to check before calling.
- Drains backing up in HoustonWhy Houston drains back up: grease and wipes cause 70% of the city's sewer overflows, and overflows double when it turns cold. Symptoms, safe checks and fixes.
- Drains backing up in OrlandoWhy Orlando drains back up: grease builds up in home lines and the city's 800-plus miles of sewer. Symptoms, safe checks, the city's oil recycling, and fixes.
- Drains backing up in Los AngelesWhy LA drains back up: grease in kitchen lines and the city's 6,600 miles of sewer, the FOG program that cut overflows 94%, and what to check before calling.
- Drains backing up in PhiladelphiaWhy Philadelphia drains back up: grease hardens in the lateral connecting homes to the sewer, sewage backs into houses, and how PWD says to dispose of it.
- Drains backing up in SeattleWhy Seattle drains back up: grease causes about a third of the city's sewer backups, the foods it comes from, safe checks, and when it's the side sewer instead.
Sources (2)
- SAWS, FAQs: everything you wanted to know about grease · checked 2026-10-03
- SAWS, Fats, Oils & Grease Ordinance · checked 2026-10-03